Presently there is need for improved plastic products which are safer in fire situations, even for vinyl chloride polymers which generally are considered to be flame resistant. While rigid vinyl chloride products have many structural applications useful in buildings and transportation vehicles, many used are also made of plasticized vinyl chloride polymers as in fabrics, upholstery, wall coverings and the like where flame resistance and smoke formation could be a problem. Government and safety regulations relating to such materials are now in effect. Not only is flame resistance to be reduced in such materials as vinyl chloride plastic products, but smoke generated by vinyl chloride polymer products in fires also must be reduced. The NBS smoke chamber is accepted as a measure of smoke generated. A number of materials have been proposed and used in vinyl chloride for this purpose, but very few have been found to be completely satisfactory. Many are not compatible or readily mixed with vinyl chloride polymers, many are colored or form colored products in vinyl chloride polymer compositions and many have adverse effects on the physical properties of vinyl chloride polymers.
U.S. Pat. No. 3,845,001 discloses the use of copper compounds alone, such as Cu.sub.2 O or mixtures of MoO.sub.3 and Cu.sub.2 O that reduce smoke production during combustion. This patent also states that "the applicability of such oxides suggests the use of other compounds" such as acetyl acetonylacetates and copper salts of carboxylic acids such as the acetates and butyrates. While cuprous oxide is satisfactory in reducing the smoke produced during the combustion of polyvinyl chloride, it results in an undesirable red color in the compounds. This coloration problem is particularly acute with the tin sulfur stabilizers used widely throughout the industry. The copper carboxylates suggested are generally unsatisfactory from other viewpoints than smoke reduction, for example, cupric formate during milling into polyvinyl chloride causes discoloration and black spots. Copper acetylacetonte causes discoloration during processing, which discoloration continues to develop undesirably on heating.
U.S. Pat. No. 3,821,151 discloses polyvinyl halides compounded with a mixture of iron powder and copper oxide and/or molybdenum oxide. Cuprous oxide is the preferred copper oxide. While amounts as low as 1 weight part are suggested, exemplary compositions contain 50 cupric oxide, 50 iron oxide, 20 iron powder, 40 cuprous oxide, and 40 molybdenum trioxide and 24 to 75 parts by weight of iron powder with cuprous oxide or molybdenum oxide and even 10 to 80 parts by weight of each. However, iron powder is an undesirable additive in many vinyl halide polymer compositions.